1. Field of the Invention
This invention relates to upright or display type refrigerating cabinets, such as are used in food markets for displaying frozen foods and the like, and has particular reference to a removable insulating cover for covering the access opening of such cabinet.
2. Description of the Prior Art
Refrigerating display cabinets of the above type, having vertical access openings therein, have been in use for many years in food stores and are highly desirable because they display frozen or refrigerated goods at substantially eye level and permit the store customer to easily reach through the vertical access opening to obtain any selected items. However, due to the vertical disposition of the access opening, cold air from the interior of the cabinet tends to spill out into the surrounding atmosphere. This not only forms a source of discomfort to customers standing in front of the cabinet, because of the resulting cold air drafts, but requires a considerable and wasteful expenditure of electrical energy in order to cause the refrigeration apparatus for the cabinet to maintain the interior of the cabinet and its contents at a desired low temperature level.
Although most cabinets of the above type provide means for producing a downward flowing curtain of refrigerated air across the access opening to retard the spilling of cold air outwardly through the opening, this measure is only partly effective and is acceptable only because of the convenience of the vertical access opening to the customers. However, on off-business hours, such as at night or on weekends and holidays, the temperature in the cabinet must still be maintained at substantially the same low temperature to prevent food spoilage, thus requiring the same large expenditures of energy, unless means can be provided to conveniently close the access opening during such times.
Heretofore, various types of covers have been proposed for closing the access openings of refrigerating cabinets of the above type during off hours. Such covers are generally of two types. For example, the U.S. Patents to G. K. Bently et al, No. 3,186,185; W. R. Donker No. 3,241,899; and W. R. Donker No. 3,542,445 disclose thin sheets of plastic which are stretched or otherwise extended over the access opening and are rolled up when not in use. Although such covers can be readily rolled into a relatively small space when not in use, they are obviously relatively poor heat insulators because of their thin sheet-like form and cannot adequately prevent the transfer of heat into the cabinet over sustained time periods. The patent to R. E. Vogel et al, 3,465,536, on the other hand, is directed to a rigid type cover constructed of relatively thick inter fitting panels of urethane foam plastic or the like. This type of cover is generally satisfactory in its insulating characteristics because of the good insulating quality of the thick plastic foam. However, such panels present a nuisance in that they are relatively large and cumbersome to handle and must be physically removed from the access opening during business hours and then replaced afterward. Further, the panels require a large storage space and must be carefully handled since the plastic foam is relatively fragile.